There's more to spider silk than just its maximum-strength engineering properties. It turns out the silk can carry vibrations across many frequencies, relaying information to the spider about what type of prey may be caught, or even what type of mate may be broadcasting its availabilty.
This is all thanks to a research group from the universities of Oxford, Strathclyde, and Sheffield. The team took the "Dirty Harry" approach and fired bullets at spider silk to study how it vibrated (they also fired lasers, which Harry Callahan didn't have, at least not in the first film). Super-high-speed cameras caught the silk being hit, and the lasers gave the researchers precise measurements of the smallest of vibrations.
Looking over the data, the researchers, who will publish their findings in the journal Advanced Materials, found that spider silk can, in a sense, carry tunes, only the tunes are particular vibrations at particular frequencies. Spiders can "hear" the vibrating frequencies by listening with their legs, through organs called slit sensillae.
"Most spiders have poor eyesight and rely almost exclusively on the vibration of the silk in their web for sensory information," said research lead Beth Mortimer, of the Oxford Silk Group at Oxford University. Luckily for the spider, found her team, the vibrations are packed with info, about the next meal, the next mate, or even the state of the web itself.
A spider can also use the vibrations to see if its home needs any repairs.
"By plucking the silk like a guitar string and listening to the 'echoes' the spider can also assess the condition of its web," Mortimer said. If there's a problem, the spider can "tune" the silk, adjusting its properties, tensions and how it interconnects with other areas.
"These findings further demonstrate the outstanding properties of many spider silks that are able to combine exceptional toughness with the ability to transfer delicate information," said the paper's author, Professor Fritz Vollrath, of the Oxford Silk Group at Oxford University.
Vollrath and his fellow researchers see two valuable prongs to their research. One, we learn a lot more about the life of spiders and the qualities of their silk; and two, we gain insight that could be helpful outside of the arachnid world.
The properties of the silk, said Vollrath, "would be very useful in lightweight engineering and might lead to novel, built-in 'intelligent' sensors and actuators."